fix: dispose keyboard leaping notifiers

lib/src/gestures/map_interactive_viewer.dart

@@ -182,6 +182,9 @@ class MapInteractiveViewerState extends State<MapInteractiveViewer>
       _keyboardListenerFocusNode.dispose();
     }
     _disposeKeyboardAnimations();
+    _isPanLeaping.dispose();
+    _isZoomLeaping.dispose();
+    _isRotateLeaping.dispose();
 
     super.dispose();
   }

test/gestures/map_interactive_viewer_test.dart

@@ -1,3 +1,7 @@
+import 'package:flutter/foundation.dart';
+import 'package:flutter/services.dart';
+import 'package:flutter/widgets.dart';
+import 'package:flutter_map/flutter_map.dart';
 import 'package:flutter_map/src/gestures/map_interactive_viewer.dart';
 import 'package:flutter_test/flutter_test.dart';
 
@@ -46,4 +50,54 @@ void main() {
       },
     );
   });
+
+  group('MapInteractiveViewerState.dispose', () {
+    Widget map() => const Directionality(
+          textDirection: TextDirection.ltr,
+          child: MediaQuery(
+            data: MediaQueryData(size: Size(800, 600)),
+            child: FlutterMap(children: []),
+          ),
+        );
+
+    testWidgets('disposes every ValueNotifier<bool> it created',
+        (tester) async {
+      final created = <Object>{};
+      final disposed = <Object>{};
+      void onEvent(ObjectEvent event) {
+        if (event.object is! ValueNotifier<bool>) return;
+        (event is ObjectCreated ? created : disposed).add(event.object);
+      }
+
+      FlutterMemoryAllocations.instance.addListener(onEvent);
+      addTearDown(
+        () => FlutterMemoryAllocations.instance.removeListener(onEvent),
+      );
+
+      await tester.pumpWidget(map());
+      await tester.pumpWidget(const SizedBox.shrink());
+
+      expect(created, isNotEmpty);
+      expect(created.difference(disposed), isEmpty);
+    });
+
+    testWidgets('can be torn down while a keyboard leap is in progress',
+        (tester) async {
+      await tester.pumpWidget(map());
+      await tester.pump();
+
+      // A short press starts a leap, which writes the leaping notifiers from
+      // the animation's listener until the curve reaches its leap maximum.
+      await tester.sendKeyDownEvent(LogicalKeyboardKey.arrowUp);
+      await tester.pump(const Duration(milliseconds: 16));
+      await tester.pump(const Duration(milliseconds: 16));
+      await tester.sendKeyUpEvent(LogicalKeyboardKey.arrowUp);
+      await tester.pump(const Duration(milliseconds: 16));
+
+      await tester.pumpWidget(const SizedBox.shrink());
+      await tester.pump(const Duration(seconds: 1));
+
+      expect(tester.takeException(), isNull);
+    });
+  });
 }